In order to adapt to different applications such as film shooting, agricultural plant protection and cargo transportation, the existing unmanned aerial vehicles (UAVs) in the market are designed to have six or even eight rotors. In this structural design, the unmanned aerial vehicles accordingly has a larger size due to the body's wheelbase is enlarged, which may result in inconvenience when storing or moving the unmanned aerial vehicles.
The rotor folding structure of the present unmanned aerial vehicle adopts, for example, a buckle type folding structure, a clip-on type folding structure or a detachable spiral arm structure. The buckle type folding structure utilizes a rotation of a buckle structure, such as clockwise or counterclockwise rotation, to achieve a position-limiting effect thereby switching the rotor between a folded state and an unfolded state. The clip-on type folding structure utilizes a clip-on structure to engage and fix the rotor arm thereby switching the rotor between a folded state and an unfolded state. The detachable spiral arm structure directly disassemblies and folds the rotor arm.
However, the above-mentioned rotor folding structure still has some problems such as insufficient fixing strength and easy to be loosened. For example, the buckle type folding structure merely tightens and fixes the rotor by means of overlapping the buckle structures and only fixes the axial position limiting, therefore, the gap will become larger and larger under the use and wear and tear for a long time. Thus, the buckle may be loosening by the vibration generated by the motor when the unmanned aerial vehicle is in flight. In addition, most of the buckle type folding structures are plastic structures; thus, the buckle is easy to be loosening when the structural fatigue, insufficient strength and wear and tear in structure occurs. The clip-on type folding structure utilizes, for example, a C-type clip-on structure to realize the fixing by overlapping the rotor arms. The C-type clip-on structure uses only a local interference to limit the rotor arm therefore cannot tightly clamp and securely fix the rotor arm. In addition, most of the C-type clip-on structures are plastic structures; thus, they also have the problems of structural fatigue and insufficient strength. The detachable spiral arm structure can effectively reduce the size of the unmanned aerial vehicle in the fold state, but the re-assembly is not only time-consuming but also may cause a higher risk that the unmanned aerial vehicle or even the rotation direction of the motor is wrong assembled. Therefore, how to improve the above-mentioned problem is the focus of attention of the related person in the field.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.